Effects of Carbon Source, Carbon Concentration and Culture Conditions on in Vitro Rooting of Pinus Pinea L. Microshoots

Abstract

Clonal propagation via adventitious bud stimulation from cotyledon explants has been reported before in stone pine (Pinus pinea L.), however the number of rooted shoots had low frequency and short growth span. Therefore the main objective of the present work was to increase the number and quality of roots per shoot in order to ensure the survival and growth of a great number of plants in the acclimation phase. To achieve this, different combinations of carbon source (sucrose or glucose) at different concentrations, under different environmental conditions (temperature and light), were tested in the induction and expression phases of the adventitious root formation. Shoots of different clones obtained via organogenesis have been employed for the experiments. Observations were made on the rooting percentage, root length and number of roots per shoot. The results showed a general increased of the number of roots per shoot and an earlier root formation when glucose was used as a carbon source. However, there were no differences in the percentage of rooting between the carbons sources tested. The best results were obtained using 0.117 M of glucose and dark treatment combined with 19 ºC during the induction phase of the rhizogenic process. Light and low sugar concentration proved to be beneficial for the expression phase, increasing the root length. A remarkable interclonal difference in the ability to form roots was observed. It was possible to obtain a rooting percentage of more than 75% in several of the tested clones.

Micropropagation of Juniperus navicularis, an endemic and rare species from Portugal SW coast

“…The elongated microshoots (2 cm long separated from any browning tissues) were then transferred to modified WPM root induction medium with half concentration of macronutrients and 5.35 lM of naphthaleneacetic acid (NAA), where they remained for 2 weeks. Culture conditions were 19°C in darkness during the first week and 19°C with 16 h photoperiod during the second week (Zavattieri et al 2009). Following the root induction treatment, the shoots were transferred to root expression medium consisting of modified WPM (half concentration of macronutrients) PGR-free medium.…”

“…Rooted shoots were washed carefully in water to eliminate residual medium and planted in pots filled with non sterile substrate mix of perlite:vermiculite:peat moss (1:1:1) (v/v) (Zavattieri et al 2009). We used a special culture chamber equipped with light and dry mist system to provide high relative humidity, and therefore it was not necessary to cover the plantlets.…”

Adventitious rooting of conifers: influence of physical and chemical factors

“…However, other carbohydrates such as glucose and fructose have been also used to improve organogenesis (Faye et al 1989;Ordás et al 1999;Zavattieri et al 2009). The exogenous sucrose (in the presence or absence of auxin) is beneficial for the rooting of most herbaceous and woody plants (Haissig 1982).…”

“…Zavattieri et al (2009) made a direct comparison between different carbon sources (sucrose or glucose at different concentrations) for the induction and expression phases of the adventitious roots in microshoots of Pinus pinaea. An increased number of roots per shoot and an accelerated root formation were consistently obtained using glucose.…”

Molecular approach to characterize ectomycorrhizae fungi from Mediterranean pine stands in Portugal

“…Inoculation with specific fungi can enhance pine root formation and/or subsequent root branching of cuttings ( Normand et al , 1996 ; Karabaghli et al , 1998 ; Niemi et al , 2000 ). Some research results demonstrated the potential use of ECM fungi in the vegetative propagation of conifers ( Gay, 1990 ; Niemi et al , 2005 ) and during in vitro rooting of pine shoots ( Zavattieri et al , 2009 ; Ragonezi et al , 20010a). Inoculations enhanced plant performance and contributed to alleviation of stress related with acclimation in a nursery and the subsequent growth in the field.…”